Thai media and officials often blame the pollution on swidden (or shifting) agriculture. Swidden farmers typically cultivate plots of land in cycles. A particular plot of land is cultivated for a year, then allowed to lie fallow and recover for multiple years before being used again. In the meantime, farmers shift to a different plot of land. In the long term, swidden farmers rotate among several plots, always moving toward old, previously cultivated land. Most swidden farmers burn plots of land in order to clear and fertilize them before planting. This practice typically falls between February and April, during the worst of the haze, and has sparked intense criticism and controversy.